Network-type heat pipe device

ABSTRACT

A network-type heat pipe device is disclosed, wherein the network-type heat pipe device comprises a heat dissipating unit with a network shape, a heat absorbing unit of any desired shape, and two single flexible capillary pipes connecting the heat absorbing unit with the heat dissipating unit. The working fluid filled in the heat pipe is of a predetermined quantity smaller than the internal volume of the heat pipe. The inside diameters of the capillary pipes of the network-shaped heat dissipating unit and the connecting capillary pipes are small enough such that the vapor and liquid segments of the working fluid may distribute therein by capillary effect. As the heat absorbing unit is heated, the mutual actions of the pushing or compression force generated due to the vaporization at the heat absorbing unit, the resisting force generated due to the vapor condensation at the heat dissipating unit, and the gravitational force generated due to the liquid segments in the vertical part of the capillary pipes in the heat dissipating unit and the connecting pipes cause a circulating flow for the working fluid to carry heat from the heat absorbing unit to the heat dissipating unit. The heat absorbing unit can be placed under the heat dissipating unit so as to enhance the gravitational force for circulating the working fluid in the single direction in the flow passage and to increase the heat transport from the heat absorbing unit to the heat dissipating unit.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a heat transfer device of anetwork-type heat pipe, wherein the heat transfer is achieved by heatabsorption from a heat source, evaporation and condensation of a workingfluid fill the device, and the heat dissipates into a heat sink. Thecapillary pipes forming the heat dissipating unit are made into anetwork shape, the heat absorbing unit may be constructed in any shapedesired for absorbing the heat; and two single capillary pipes are usedto connect the heat absorbing unit and the heat dissipating unit.

[0003] 2. Description of the Prior Art

[0004] The conventional heat transfer device of heat a pipe is formed bya pipe, a capillary structure or wick, and a working fluid. In general,a pipes is made of a straight metal tube. The hollow capillary structuremade of a porous medium adheres to the inner wall of the tube and formsa hollow channel for the vapor of a working fluid to pass through. Theworking fluid, such as alcohol, methyl alcohol or water, fills the heatpipe. When one end of the heat pipe (the evaporator) is heated, theliquid working fluid absorbs the heat and evaporates to form a vapor.The vapor then flows out from the capillary structure in the evaporatorto another end of the heat pipe (the condenser). The vapor thencondenses as a liquid and penetrates the capillary structure in thecondenser, while the condensed heat dissipates outwards. The condensedliquid is transferred back to the evaporator through a capillarystructure by capillary effect to repeat the process of heating andevaporating and complete a cycle. There are three main defects in theconventional heat pipe: (1) it is made of hard straight tubes so that itlacks flexibility in installation; (2) the use of a capillary structureor porous medium in a heat pipe causes additional cost and qualitycontrol problems; (3) the distance of heat transport is limited by thecapillary structure. In order to improve the defects of theaforementioned conventional heat pipe, in the prior art the heat pipe ismade as a closed loop and the inner part of the loop has no capillarystructure. The loop is mounted vertically with the evaporator at thelower part of a vertical leg and the condenser is mounted at the upperpart of another vertical leg. A working fluid, such as alcohol, methylalcohol or water, fills the loop. When the evaporator is heated, theworking fluid absorbs the heat and vaporizes to form a vapor. The vaporthen flows to the condenser at the upper part of another vertical legand condenses as liquid. The condensation heat dissipates outwards toachieve the heat transport, while the condensed liquid flows back to theevaporator by the gravitational force to complete a flow cycle. Thiskind of heat pipe is call as a “thermosyphon-loop heat pipe”, the majordefect of which is that the condenser and the evaporator are generallyinstalled on a vertical plane with a short horizontal distance betweenthem so as to minimize the frictional force of the working fluid flowingthrough the connecting tubes between the two legs.

[0005] In order to improve the defects of the conventional heat pipes,in U.S. Pat. Nos. 4,921,041 (1990) and 5,219,020 (1993), filed byAkachi, Japan, the aforementioned single-loop thermosyphon heat pipe isdesigned as a multiple-loop capillary heat pipe which is connected in aseries to a bundle of parallel capillary pipes. The two ends of the heatpipe are interconnected to form a closed loop. The inner part of thepipe is empty (referring to FIG. 1). An evaporating unit (11) of themultiple-loop capillary heat pipe is on one side and a condensing unit(12) on another side. Heat is transported from the evaporating unit 11via the condensing unit 12 to the heat sink. The pipe is a designed ascapillary tube in order to provide capillary effect. The pipe is filledwith working fluid (such as alcohol, methyl alcohol, freon or water) atan appropriate volume ratio. Before operation of the heat pipe, theliquid working fluid is distributed in segments along the multiple-loopheat pipe by capillary effect, and vapor segments fill in between theliquid segments.

[0006] As the evaporating unit is heated, the liquid absorbs heat andvaporizes. The vapor bubbles start to grow and the pressure increases soas to push the liquid and vapor segments to flow toward the lowertemperature end (condensing unit). The condensation of the vapor in thecondensing unit at a lower temperature lowers the pressure and furtherenhances the pressure difference between the two ends of the evaporatingand condensing unit. Because of the inter-connection of the pipe, themotion of liquid and vapor segments in one section of the tube towardthe condenser also leads to the motion of liquid and vapor segments inthe next pipe section toward the high temperature end (evaporator) inthe next section. This works as a restoring force. The interactionbetween the driving force and the restoring force leads to oscillationof the liquid and vapor segments in the axial direction. Therefore, thiskind of heat pipe is called a “Pulsating heat pipe” or a “Capillary loopheat pipe”. The frequency and amplitude of the oscillation are dependenton heat flow and mass fraction of the liquid in the pipe. There are twodefects in this heat pipe: (1) the manufacturing of the capillary loopheat pipe with at least three pipe turns, or several tens or hundreds ofturns is difficult and, in particular, the connection between theevaporating unit and the condensing unit is not easy; (2) the wholelength of the capillary loop heat pipe must be made from a singlecapillary tube in order to form a single closed loop (with multipleturns). The design flexibility in practical application is thereforeconfined.

SUMMARY OF THE INVENTION

[0007] Accordingly, the object of the present invention is to provide aheat transfer device using network-shaped capillary pipes, wherein theheat absorbing unit may be any desired shape; The heat dissipating unitand the heat absorbing unit are connected by two single capillary pipes(one inlet and one outlet), therefore, it may be easily manufactured. Acondensable working fluid fills the device.

[0008] According to the main goal of the present invention, it providesa network-type heat pipe device using capillary pipe, the heat transportis achieved by the heat absorption from a heat source in the heatabsorbing unit, vaporization and condensation of a working fluid, andheat dissipation to a heat sink in the heat dissipating unit. Thecapillary pipes forming the heat dissipating unit are formed in anetwork shape. The heat absorbing unit may be formed in any desiredshape for easy mounting to a heat source.

[0009] According to the aforementioned concept, the inner part of theheat absorbing unit may be made as an empty space in any desired shapeso that the working fluid may flow therewith, and two single capillarypipes are used to connect the heat absorbing unit and the heatdissipating unit in each inlet and outlet. The heat absorbing unit canbe installed at a position below the heat dissipating unit for betterperformance.

[0010] According to the above concept, a working fluid (such as alcohol,methyl alcohol, Freon, or water, etc.) is filled in the heat absorbingunit, the heat dissipating unit and the connecting capillary pipes.Before operation, the capillary effect causes the working fluid to formas piece-wise liquid segments along the pipes, and vapor segments fillin between the liquid segments.

[0011] After startup, the liquid working fluid in the heat absorbingunit absorbs heat from a heat source and evaporates to form apressurized vapor to flow out and compress the vapor segments (orbubbles) in the network-type capillary pipes of the heat dissipatingunit. The compression of the vertical vapor segments in the capillarynetwork of the heat dissipating unit causes an increase in the netgravitational force and the liquid flows down and back to the heatabsorbing unit. The liquid in the heat absorbing unit continues tovaporize, and the vapor flows to the heat dissipating unit wherein thevapor condenses as liquid. The vaporized vapor in the heat absorbingunit also pushes the vapor bubbles and liquid segments within thenetwork pipes of the heat dissipating unit along a direction, while thevapor segments in the heat dissipating unit condense due to the heatdissipation to the heat sink. The vapor pushing force from the heatabsorbing unit and the vapor condensation makes the vertical liquidsegments merge together downstream and induces a net gravitational forcefor the liquid to flow back to the heat absorbing unit so as to completea flow cycle. Heat is then absorbed at the heat absorbing unit andreleased at the heat dissipating unit.

[0012] During the startup or transient period, some liquid segments mayexist inside the connecting pipe for the outflow from the heat absorbingunit to the heat dissipating unit. The vaporized vapor in the heatabsorbing unit pushes the vapor and liquid segments in the connectingpipe toward the heat dissipating unit. The vertical liquid segments inthe outflow pipe thus act as a resisting force to the net gravitationalforce for the liquid flow back to the heat absorbing unit through theinflow connecting pipe. The condensation of the vapor in the heatdissipating unit at a lower temperature causes a lower pressure andfurther enhances the pressure difference for the flow from the heatabsorbing unit to the heat dissipating unit, but it in turn reduces thedownward force for the liquid back flow to the heat absorbing unit.Therefore, the vapor and liquid of the working fluid will form apulsating motion following the interaction of the evaporating pressureby heating, the lower vapor pressure force by vapor condensation, andthe resisting force by the vertical liquid segments in the outflow ofthe heat absorbing unit. The liquid segments within the connecting pipefor the outflow of the heat absorbing unit will gradually flow into thehorizontal part of the network pipe in the heat dissipating section.After the liquid segments within the connecting pipe for the outflow ofthe heat absorbing unit have been cleared up, a constant netgravitational force will be built and a steady flow along one directionwill form. The process finally comes to a steady state and heat istransported steadily from the heat absorbing unit to the heatdissipating unit.

[0013] The present invention will be better understood and its numerousobjects and advantages will become apparent to those skilled in the artby making reference to the attached drawings, described below.

BRIEF DESCRIPTION OF DRAWINGS

[0014]FIG. 1 shows the structure of the capillary loop heat pipe devicein the prior art.

[0015]FIG. 2 shows the structure of the network-shape heat pipe deviceof the present invention.

[0016]FIG. 3 is a cross section view of the network-shape heat pipedevice of the present invention.

[0017]FIG. 4 is the structure of the heat absorbing unit of the presentinvention at a different orientation.

[0018]FIG. 5 is the network-shape capillary pipe of the heat dissipatingunit in the present invention, with a different network shape.

[0019]FIG. 6 shows the structure of the heat absorbing unit in thepresent invention.

[0020]FIG. 7 is an expanded view of the heat absorbing unit in thepresent invention.

[0021]FIG. 8 shows the structure of the heat dissipating unit, which isattached to a heat dissipating plate.

[0022]FIG. 9 shows the structures of the heat absorbing unit and theheat dissipating unit of the present invention.

[0023]FIG. 10 shows the test results of the present invention.

[0024]FIG. 11 shows the heat dissipating unit and the heat absorbingunit with the network-shape capillary pipe structure of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0025] Referring to FIG. 2, the structural schematic view of thepreferred embodiment of the present invention is shown, wherein thenetwork-type heat pipe device of the present invention comprises: a heatabsorbing unit (1), the inside of which may be formed as a desired spaceso that the working fluid will flow within, with only a single capillarypipe connected on inlet 3 and outlet 4 thereof; a heat dissipating unit(2) made from the capillary pipes, which is formed as a network shape; asingle capillary pipe ( 3, 4) which links the heat dissipating unit 2and the heat absorbing unit 1; and a working fluid (such as alcohol,methyl alcohol, water, etc.) which fills the heat absorbing unit 1 andthe capillary pipes. The amount of working fluid is approximately equalto 30% to 60% of the total inside volume. Before operation, capillaryeffect causes the working fluid to form as piece-wise liquid segments(21) distributed along the pipes, and vapor segments (22) fillingbetween the liquid segments 21.

[0026] Now referring to FIG. 3, the cross section view of FIG. 2 isshown. Also, according to the aspects of FIGS. 2 and 3, when the heatdissipating unit 2 is arranged above the heat absorbing unit 1 and afterstartup as the heat absorbing unit 1 is heated, the liquid working fluidabsorbs heat and evaporates to form a pressurized vapor to flow out andcompress the vapor segments (or bubbles) 22 in the network made ofcapillary pipes in the heat dissipating unit 2. The compression of thevertical vapor segments in the capillary network of the heat dissipatingunit 2 causes an increase in the net gravitational force for the liquidto flow down to the heat absorbing unit 1. The liquid in the heatabsorbing unit I continues to vaporize, and the vapor flows to the heatdissipating unit 2 wherein the vapor condenses as liquid. The vaporizedvapor in the heat absorbing unit 1 also pushes the vapor bubbles 22 andliquid segments 21 within the network pipes of the heat dissipating unit2 along a direction, while the vapor segments 22 in the heat dissipatingunit 2 condense and heat is ejected to the heat sink. The vapor pushingforce from the heat absorbing unit 1 and the vapor condensation in theheat dissipating unit 2 makes the vertical liquid segments mergetogether at downstream and induces a net gravitational force for theliquid to flow back to the heat absorbing unit 1 so as to complete aflow cycle. Heat is thereby absorbed at the heat absorbing unit 1 andreleased at the heat dissipating unit 2.

[0027] During the startup or transient period, some liquid segments 21may exist inside the connecting pipe 3 for the outflow from the heatabsorbing unit 1 to the heat dissipating unit 2. The vaporized vapor inthe heat absorbing unit 1 pushes the vapor and liquid segments in theconnecting pipe 3 toward the heat dissipating unit 2. The verticalliquid segments in the outflow pipe thus act as a resisting force to thenet gravitational force for the liquid flow back to the heat absorbingunit 1 through the other connecting pipe 4. The condensation of thevapor in the heat dissipating unit 2 at a lower temperature causes alower pressure and further enhances the pressure difference for the flowfrom the heat absorbing unit 1 to the heat dissipating unit 2, but it inturn reduces the downward force for the liquid back flow to the heatabsorbing unit 1. Therefore, the vapor and liquid of the working fluidwill form a pulsating motion following the interaction of theevaporating pressure by heating, the lower vapor pressure force bycondensing and the resisting force by the vertical liquid segments inthe outflow of the heat absorbing unit. The liquid segments within theconnecting pipe 3 for the outflow of he heat absorbing unit 1 willgradually flow into the horizontal part of the network pipe in the heatdissipating section 2. After the liquid segments within the connectingpipe 3 for the outflow of the heat absorbing unit 1 have been clearedup, a constant net gravitational force will be built and a steady flowalong one direction will form. The process finally comes to steady andheat is transported steadily from the heat absorbing unit to the heatdissipating unit.

[0028] According to FIGS. 2 and 3, the heat dissipating unit 2 may bearranged on any orientation. The heat absorbing unit 1 may be arrangedhorizontally or vertically (referring to FIG. 4). The relative positionof the heat dissipating unit 2 and the heat absorbing unit 1 may bearranged at will. However, as the heat dissipating unit 2 is arrangedabove the heat absorbing unit 1, the gravitational effect of thevertical liquid segments will enhance the heat pipe performance. Thus, apreferred heat transfer is achieved.

[0029] According to FIGS. 2 and 3, the heat dissipating unit 2 is madefrom capillary pipes and as a network shape, further it may be made asall inter-network shape. In addition, it may be simplified as aparallel-shape network, as shown in FIG. 5, for easier manufacturing.

[0030] According to FIGS. 2 and 3, the connecting capillary pipes (3, 4)may be made from a flexible metal, polymer, or macro-molecular material.

[0031] According to FIGS. 2 and 6, the inner part of the heat absorbingunit 1 may be made as an empty space (105) as required. The ports(103,104) thereof connect to two capillary connectors (101, 102). Theoutlook shape of the heat absorbing unit 1 may be made as a flat box asshown in FIG. 6 so that it can be easily adhered to the heating body.The heat absorbing unit 1 includes an inlet connector 101, an outletconnector 102, an evaporating chamber 105, an inlet port 103, and anoutlet port 104. In order to allow for easy manufacturing, the heatabsorbing unit 1 may be designed with upper and a lower halves (106 and107), which are then joined together at a surface 100. The inletconnector 101 is installed on the lower half 107 for receiving theliquid working fluid flowing into the evaporating chamber 105 which isthen evaporated by heating. The outlet connector 102 is installed on theupper half 106 for guiding the vapor to flow out of the evaporatingchamber 105. The expanded view of the upper and lower halves (106 and107) are shown in FIG. 7.

[0032] Referring to FIG. 8 again, according to FIGS. 2, 4, and 5, theheat dissipating unit 2 made from the network-shape capillary pipe maybe adhered on a heat dissipating plate 5 for enhancing the heatdissipating ability thereof.

[0033] According to FIGS. 2, 4, 5, and 8, the shapes of the heatabsorbing unit 1 and the heat dissipating unit 2 may be interchanged.Referring to FIG. 9 again, the heat absorbing unit 61 can be made as anetwork-shape capillary pipe, while the heat dissipating unit 62 may bemade as a flat box as shown in FIG. 6 with empty space inside so that itcan be easily adhered to a heat sink. Two single capillary pipes (3,4)are used to connect the heat dissipating unit 62 and the heat absorbingunit 61.

[0034] In order to verify the concept of the present invention, theinventor has fabricated a prototype of a “network-type heat pipe device”for testing according to the structure of FIG. 8. The heat absorbingunit 1 is designed according to the structure of FIG. 6, with dimensions50 mm long, 50 mm wide, and 8 mm high. The structure of the heatdissipating unit 2 is shown in FIG. 8. The area of the heat dissipatingplate 5 is 300mm by 200mm, and has an 80 degree tilt angle. The insidediameter of the network-shape capillary pipe of the heat dissipatingunit 2 is 1.8 mm. The capillary pipes (3 and 4) linking the heatabsorbing unit 1 and the heat dissipating unit 2 are made frompolycarbonate (PC) tubes with an outside diameter 4 mm. A disk-typethin-film electric heater with 19 ohms resistance is adhered under theheat absorbing unit 1, which is heated by a DC power supply to simulatea heat source. A heat insulating material is installed under theelectric heater and on the outside surface of the connecting capillarypipe (3, 4) for reducing the heat loss so that the heating rate of theelectric heater is approximately equal to the heat absorption rate ofthe heat absorbing unit 1 or the heat dissipation rate (Q) of the heatdissipating plate 5. During testing, no fan is used to enhance the heattransfer of the heat dissipating plate 5. The heat is dissipated bynatural convection to the ambient. The testing results are shown in FIG.10 and Table 1, wherein the filling quantity of the working fluid is 50%of the total volume. Therein the temperature difference (ΔT=T_(h)−T_(a))is defined as the temperature difference between the heat absorbing unit1 (T_(h)) and the temperature of the atmosphere (T_(a)). The definitionof thermal resistance R is (T_(h)−Ta)/Q, which represents the resistanceof the heat transfer from the heat absorbing unit 1 (or heat source) tothe ambient. It is shown from FIG. 10 and Table 1, under the conditionof natural convection for the heat dissipating plate 5, thenetwork-shape heat pipe fabricated by the inverter can dissipate 30W forthe temperature difference (ΔT) at 32° C., the thermal resistance R is1.07° C./W. The performance is superior to the other means. If it isused for the heat dissipation of notebook computers, this is superior tothe prior heat dissipating technology. Referring to FIG. 11, both theheat absorbing unit 1 and the heat dissipating unit 2 can also be madeof capillary pipes and as a network shape or parallel-type network(referring to FIG. 5) heat pipe device. The heat absorbing unit 1 andthe heat dissipating unit 2 are linked by two single capillary pipes (3,4). The network-shape capillary pipes of the heat absorbing unit 1 andthe heat dissipating unit 2 may also be adhered on a plate for enhancingthe heat transfer (referring to FIG. 8). TABLE 1 heat absorptiontemperature of heat temperature amount absorbing unit of atmospheretemperature heat resistance (Th— Q. W Th, ° C. Ta, ° C. Th—Ta, ° C.Ta)/Q, R, ° C./W 30.0 61.2 29.2 32.0 1.07 250 56.6 29.3 27.3 1.09 20.053.6 29.4 24.2 1.21 15.0 49.6 29.6 20.0 1.33 10.0 45.1 29.7 15.4 1.545.0 40.1 29.4 10.7 2.14 3.9 40.8 32.0 8.8 2.26 2.9 40.9 31.8 9.1 3.14

[0035] The present invention can be widely used in the heat dissipationof heat generating bodies, such as in computer or electronic devices(CPU, IC chips, power supplies, optic disks, or hard disks), homeappliances (refrigerators, air conditioners, dehumidifiers, solar energycollectors), or other products or processes requiring heat transportfrom one place to another.

[0036] Although a certain preferred embodiment of the present inventionhas been shown and described in detail, it should be understood thatvarious changes and modifications may be made therein without departingfrom the scope of the appended claims.

What is claimed is:
 1. A heat pipe device used in heat transport,comprising: (a) a heat absorbing unit inside of which is a space of anyshape for storing working fluid; the heat absorbing unit being used toabsorb heat from a heat source; (b) a heat dissipating unit formed bynetwork-shape capillary pipes for releasing the heat transported fromthe heat absorbing unit to a heat sink; (c) two connecting capillarypipes having a single tube shape and being made from an extensible metalor nonmetal material for connecting to each end of heat absorbing unitand heat dissipating unit so as to form a closed loop; (d) a condensableworking fluid filled in the heat absorbing unit, the heat dissipatingunit, and the connecting capillary pipes, wherein the quantity of thefilled liquid is smaller than the total volume of the inner spaces ofthe heat absorbing unit, the heat dissipating unit and the connectingcapillary pipes.
 2. The heat pipe device as claimed in claim 1 , whereinthe inner spaces of the heat absorbing unit the heat dissipating unit,and the connecting capillary pipe are linked so that the condensableworking fluid is sealed within and may flow within.
 3. The heat pipedevice as claimed in claim 2 , wherein the inside diameters of thecapillary pipes of the network-shape heat dissipating unit and theconnecting capillary pipes are small enough such that the vapor andliquid segments of the working fluid may distribute herein by capillaryeffect, wherein as the heat absorbing unit is heated, the mutual actionsof the pushing or compression force generated due to the vaporization atthe heat absorbing unit, the resisting force generated due to the vaporcondensation at the heat dissipating unit, and the gravitational forcegenerated due to the liquid segments in the vertical part of thecapillary pipes in the heat dissipating unit and the connecting pipescause a circulating flow for the working fluid to carry heat from theheat absorbing unit to the heat dissipating unit.
 4. The heat pipedevice as claimed in claim 3 , wherein the heat absorbing unit isinstalled under the heat dissipating unit so as to enhance thegravitational force for circulating the working fluid in a singledirection in the flow passage and to increase the heat transport fromthe heat absorbing unit to the heat dissipating unit.
 5. The heat pipedevice as claimed in claims 3 or 4, wherein the heat dissipating unit ismade of network-shape capillary pipes having at least two parallel rowsof capillary pipes the inner part of which are connected with eachother.
 6. The heat pipe device claimed in claims 3 or 4, wherein thenetwork-shape capillary pipes in the heat dissipating unit is adhered ona plate for enhancing the heat transfer to the heat sink.
 7. The heatpipe device as claimed in claims 3 or 4, wherein the heat dissipatingunit is made of network-shape capillary pipes having at least twoparallel rows of capillary pipes, the inner part of which are connectedwith each other, and the network-shape capillary pipes are adhered on aplate for enhancing the heat transfer to the heat sink.
 8. The heat pipedevice as claimed in claims 3 or 4, wherein the heat absorbing unit maybe made as a flat-box shape and includes an inlet port, an outlet port,an evaporating chamber, characterized in that: The heat absorbing unitmay be designed with upper and a lower halves, that are then joinedtogether as a whole body; The inlet port for the working fluid isinstalled on the lower half for receiving the liquid working fluidflowing into the evaporating chamber; The outlet port is installed onthe upper half for guiding the vapor to flow out of the evaporatingchamber.
 9. A heat pipe device used in heat transport, comprising: (a) aheat absorbing unit formed by network-shape capillary pipes forabsorbing heat from a heat source; (b) a heat dissipating unit insidewhich has a space of any shape for storing working fluid, the heatdissipating unit being used to dissipate the heat to a heat sink; (c)two connecting capillary pipes having a single tube shape and having anextensible metal or nonmetal material for connecting heat absorbing unitand heat dissipating unit so as to form a closed loop; (d) a condensableworking fluid filled in the heat absorbing unit, the heat dissipatingunit, and the inner space of the connecting capillary pipes, wherein thequantity of filled liquid is smaller than the total volume of the innerspace of the heat absorbing unit, the heat dissipating unit and theconnecting capillary pipes.
 10. The heat pipe device as claimed in claim9 , wherein the inner spaces of the heat absorbing unit, the heatdissipating unit, and the connecting capillary pipe are linked so thatthe condensable working fluid is sealed within and may flow within. 11.The heat pipe device as claimed in claim 10 , wherein the insidediameters of the network-shape capillary pipes of the heat absorbingunit and the connecting capillary pipe are small enough so that thevapor and liquid of the working fluid may distribute therein bycapillary effect.
 12. The heat pipe device as claimed in claim 11 ,wherein the heat absorbing unit is installed under the heat dissipatingunit so as to enhance the gravitational force for circulating theworking fluid in the single direction in the flow passage and toincrease the heat transport from the heat absorbing unit to the heatdissipating unit.
 13. The heat pipe device as claimed in claims 11 or12, wherein the heat absorbing unit is made of at least two parallelrows of capillary pipes the inner part of which are connected with eachother.
 14. The heat pipe device as claimed in claims 11 or 12, whereinthe network-shape capillary pipes in the heat absorbing unit are adheredon a plate for enhancing the heat dissipation to the heat sink.
 15. Theheat pipe device as claimed in claims 11 or 12, wherein the heatabsorbing unit is made of at least two parallel rows of capillary pipesthe inner part of which are connected with each other, and thenetwork-shape capillary pipes are adhered on a plate for enhancing theheat dissipation to the heat sink.
 16. A heat pipe device used in heattransport, comprising: (a) a heat absorbing unit made of network-shapecapillary pipes, the heat absorbing unit being used to absorb heat froma heat source; (b) a heat dissipating unit made of network-shapecapillary pipes for releasing heat to a heat sink; (c) two connectingcapillary pipes having a single tube shape and having an extensiblemetal or nonmetal material for connecting heat absorbing unit and heatdissipating unit so as to form a closed loop; (d) a condensable workingfluid filled within the heat absorbing unit, the heat dissipating unit,and the inner space of the connecting capillary pipes, wherein thequantity of filled liquid is smaller man the total volume of the innerspaces of the heat absorbing unit, the heat dissipating unit and theconnecting capillary pipe.
 17. The heat pipe device as claimed in claim16 , wherein the inner spaces of the heat absorbing unit, the heatdissipating unit, and the connecting capillary pipe are linked so thecondensable working fluid is sealed within and may flow within.
 18. Theheat pipe device as claimed in claim 17 , wherein the inside diametersof the network-shape capillary pipes in the heat dissipating unit andthe heat absorbing unit and the connecting capillary pipes are smallenough such that the vapor and liquid segments of the working fluid maydistribute therein by capillary effect, so that as the heat absorbingunit is heated, the mutual actions of the pushing or compression forcegenerated due to the vaporization at the heat absorbing unit, theresisting force generated due to the vapor condensation at the heatdissipating unit, and the gravitational force generated due to theliquid segments in the vertical part of the capillary pipes in the heatdissipating unit and the connecting pipes cause a circulating flow forthe working fluid to carry heat from the heat absorbing unit to the heatdissipating unit.
 19. The heat pipe device as claimed in claim 18 ,wherein the heat absorbing unit is installed under the heat dissipatingunit so as to enhance the gravitational force for circulating theworking fluid in the single direction in the flow passage and toincrease the heat transport from the heat absorbing unit to the heatdissipating unit.
 20. The heat pipe device as claimed in claims 18 or19, wherein the heat dissipating unit and the heat absorbing unit aremade of at least two parallel rows of capillary pipes the inner part ofwhich are connected with each other.
 21. The heat pipe device as claimedin claims 18 or 19, wherein the network-shaped capillary pipes in theheat dissipating unit and the heat absorbing unit are adhered on a platefor enhancing the heat dissipation to the heat sink.
 22. The heat pipedevice as claimed in claims 18 or 19, wherein the heat dissipating unitand the heat absorbing unit are made of at least two parallel rows ofcapillary pipes, the inner part of which are connected with each other,and the network-shape capillary pipes is adhered on a plate forenhancing the heat dissipation to the heat sink.